Skip to main content

Full text of "Text Book Of Mechanical Engineering"

See other formats


812                             Appendix IL

milling machine intended to directly supplant planers, shapers
and slotters, even for ordinary unrepeated work. Over and over
again has it been proved that this can be done with economy,
despite renewal cost of mills, while the finish of the work is un-
doubtedly better. Fig. 780 is a vertical machine to do slotting-
machine work, and the horizontal machine Fig. 781 similarly
serves for planed work; the table movements giving feed in both
cases, and not cut. (Seep. 1020.)

Special Copying Machines.—The copying principle has
an extreme illustration in such apparatus as the copying lathe and
I!                                the profiling machine.   The former was the invention of Blanchard,

|                                an American, and was used by him to make such articles as shoe-

I] *                         makers' lasts, gun-stocks, &c.   It is still much adopted for ' turning'

*i                         the spokes and felloes of wooden wheels, and its principle will be

I i                       understood from Fig. 782.    There are two fixed headstocks, A

I /                       and B, and two corresponding poppet heads.    In B is placed a

cast-iron copy, say a spoke, and in A a rough piece of w6od. A
sliding carriage c carries a roller D and a fly-cutter E of equal
diameter, the latter being driven at high velocity by means of a
belt. The roller D is pressed against the copy by the pull of
weight F on the carriage, and the fly-cutter gouges out the wood
in imitation of the copy. The feed must also be given. This is
obtained by &very slow rotation of the mandrel B, which is com-
municated to the second mandrel through the idle wheel G, and
as the roller D is moved backward or forward, the same movement
occurs on the cutter E, so that the copy is accurately reproduced
at any section, whatever its shape. At the same time a slow
traverse is given to the carriage along the bed, thereby including
all sections of the work,

The profiling machine is similar in character, but is arranged
vertically, and is used for metal-cutting, its progenitor being
retained for woodwork. Referring to Fig. 783, A is' the copy, B
the work, c the milling cutter, and D a 'dummy' to traverse the
•copy, the carriage E being pulled leftward as before. An enlarged
view of the dummy at r>2 shews the cone shape which is required
to gradually increase the depth of cut, by refixuig at a higher
position after each traverse. The bed is long, and similar to thai                   f

of a planing machine, the feed being caused by a slow movement                   j